The history of semiconductor devices has been characterized by a constant drive toward lower dimensions in order to increase integration density, system functionality and performance. However, this is still far from being comparable with the performance of natural systems such as human brain. The challenges facing semiconductor technologies in the millennium will be to move toward miniaturization. The influence of this trend on the quantum sensing of infrared radiation is one example that is elaborated here. A new generation of infrared detectors has been developed by growing layers of different semiconductors with nanometer thicknesses. The resulted badgap engineered semiconductor has superior performance compared to the bulk material. To enhance this technology further, we plan to move from quantum wells to quantum wire and quantum dots.

The article shows the most important experimental results describing the properties of nitride layers on GaN single crystals. The layers were grown using metal-organic chemical vapor deposition (MOCVD). The growth was monitored by in-situ laser reflectometry. The layers contain very small dislocation density of about 10 to 103 cm$min2 (the same as in GaN substrates). Morphology and crystallographic quality was examined using atomic force microscopy and X-ray diffraction. The layers have excellent photo luminescent properties which have a direct impact on the optoelectronic device properties.

Two dimensional hole gas (2DHG) created at modulated doped Al1- xGaxAs/GaAs heterostructures was studied by optical methods. Samples of different 2DHG concentration p=9.8*1011 cm$min2 were examined by means of photo luminescence (PL) and photo luminescence excitation (PLE) measurements under magnetic field up to 8T in Faraday configuration. In PL spectra two groups of lines are observed: a broad line at lower energy so called H-band and at higher energy exciton related lines. In magnetic field H-band splits and shifts linearly following Landau level quantization whereas higher energy lines exhibit diamagnetic shift. A strong absorption of H-band in PLE spectra is observed. We propose consistent theoretical model which explains both the nature of H-band and the formation of excitons on 2DHG states.

Cd1-4PbxSe thin films with 0DEGC, in an alkaline medium (pH equals 11) and studied through the structural, optical and electrical transport properties. X- ray diffraction studies revealed that pure CdSe exists in both hexagonal and cubic phase structures whereas PbSe is only cubic. The interplanar distance, d, changed from 3.528 A0 to 3.580 A0 for the change of x from 0 to 0.2 showing the formation of an alloy in 0aSigma'S), carrier concentration (n), carrier mobility ((mu) ) and the intergrain barrier potential ((Phi) B) were estimated from the above data and their variation with the temperature and film composition have been studied.

Stresses and strains are almost always present in thin films deposited on substrates. In the majority of cases they are residual stresses, introduced into the system during deposition or subsequent processing. The significant reasons of lattice stress (macrostress) formation in thin films are thermal and/or epitaxial mismatch between the thin film and substrate thermalcoefficients and lattice parameters. When using physical methods (as r.f. reactive sputtering) in order to prepare ZnO films, the compressive stresses arise as a consequence of ion bombardment with energies of tens or hundreds of electron volts by a process of atomic preening. If the deposition takes place under higher substrate temperature, the relaxation of residual stresses in the lower sublayers (close to the thin film - substrate interface) of thin film structure can occur so that the lattice stress gradient in thin film is created. The anisotropic nature of compressive stress in thin films supports the preferentially oriented growth of grains in polycrystalline thin films. A simple method to evaluate the lattice stress gradients in ZnO films by using X-ray diffraction analysis of asymmetric line profiles is presented.

X-ray sensitivity of amorphous selenium (a-Se films approximately 130 micrometers ) has been studied as a function of thickness (approximately 2400A to 7500A) of polyvinyl carbazole (PVK) interface barrier layer using the potential decay technique. The films show maximum sensitivity when incorporated with barrier layer of thickness approximately 7500A. This has been attributed to the blocking, trapping and field enhanced mobility role of the PVK interface barrier layer.

Plasma spraying technique was used for deposition of Al and Ni-Al coatings with special electrochemical characteristics. Influence of the plasma spraying process on characteristics of plasma stream and properties of the deposited coatings was investigated. Temperature field in the plasma torch, dependence of temperature of the probe placed in the plasma stream on the gas flux, pressure in the deposition chamber and arc discharge output power were measured experimentally. Surface morphology of th3 coatings by optical microscope and scanning electron microscope was investigated. It was found high dependence of the morphology on composition of the plasma gas. X-ray technique for investigation of chemical composition of the coatings was used. It was found that inter-diffusion of nickel and aluminum during deposition of the coatings takes part. This phenomenon influences chemical composition of the surface and electro-chemical characteristics of the coatings.

The modulation of composition and electro-physical properties of Hg0.8Cd0.2Te by laser annealing without melting is investigated. Concentration of Hg, Cd, Te as a function of the depth from the irradiated surface, for samples with the same composition, but with different types of electrical conductivity as well as with different initial concentrations of intrinsic defects (vacation and interstitial mercury atoms) were measured before and after laser annealing. The possible explain the unexpected oscillations regularly repeated in each sample, basing upon the thermodynamic theory of decomposition of solid solution having an unbalancing thermodynamic equilibrium and basing on change the electrical properties after treatment is presented.

The technologies of fabrication of thin film phosphors based on gallium nitride using rf-magnetron sputtering are developed and properties of films are studied. The dependence of GaN-Mn thin films deposition rate on rf-discharge power, substrate temperature and working gas pressure was estimated. The influence of technological conditions of deposition on crystal structure parameters of gallium nitride thin films were investigated. Luminescence and electron spin resonance (ESR) spectra of GaN-Mn thin films have been studied.

The growth of Hg1-xCdxTe layers obtained by pulse deposition technique on planar and non-planar patterned Si substrates with the tetragonal pyramids and the hemispherical plates was investigated by SEM, TEM spectroscopy, X-ray diffraction, X-ray analysis and I-V characterization. The effects of the Si substrate type, feature of the substrate patterns, substrate temperature, laser shots number on morphological stability of films, growth mode, films crystallinity and charge transport mechanisms on both Hg1- xCdxTe/Si interface and on Hg1-xCdxTe surface were discussed. The PLD growth of Hg1-xCdxTe films on Si substrates has been optimized both to the formation of stoichiometric films (x=0.2) and to the preparation of x-variable films.

The paper presents the results of work concerning the elaboration of GaN pseudo-bulk technology. The growth mechanism of epitaxial lateral overgrowth (ELO) GaN affected by mask patterns and the MOVPE growth process parameters are presented and discussed. The conditions to obtain full coalescence of isolated stripes leading to pseudo-bulk GaN substrate growth are specified.

Heteroepitaxial PbTiO3 and (Ba1-xSrx)TiO3 thin films were obtained by the RF sputtering method. The (100) cuts of MgO single crystals were used as substrates. The films exhibited ferroelectric properties closely similar to those of the ceramic targets. Depending on substrate temperature (Ts) with other deposition parameters constant, heteroepitaxial films of various degree of perfection of the crystalline structure were obtained. It has been found that the crystal structure of the PbTiO3//(100) MgO and (Ba1-xSrx)TiO//(100)MgO films for x<0.3 at room temperature belongs to the tetragonal system P4mm. Phase transitions in the (Ba1-xSrx)TiO3//(100)MgO films unlike those in the PbTiO3//(100)MgO films exhibited marked broadening. The domain structure of the heteroepitaxial films in comparison with that of the free ferroelectric single crystals shows certain singular features. The PbTiO3//(100)MgO films exhibit characteristic a-c-domain structure while the (Ba1-xSrx)TiO3//(100)MgO films have c-c-domain structure.

In the paper, an analysis of experimental conditions of pulsed laser deposition (PLD) of AIIBVI ternary alloy layers is presented. The growth conditions and photoelectric parameters of the layers have been measured. Two lasers were used for the ablation: YAG:Nd3+ and excimer XaCl. Photo-electrical properties of HgCdTe layers have been measured in the spectral range of 4-11 micrometers . Electro-physical properties confirmed the high carrier mobilities and low electron concentrations. Crystallographic quality of the layers has been varied depending on the kind of substrate. Their structure changes from amorphous via polycrystalline to the oriented mosaic. The PLD method allows easily obtaining periodic structures of varying layers composition with period d<10A.

LPE growth of Ga1-xAlxAsySb1-y on (100) GaSb substrates has been investigated for wide range of aluminum content in the melt, xAl1=0.01 - 0.06, various growth temperatures, and various amount of supersaturation. Epilayers were characterized by means of XRD, TEM, EPXMA, and SIMS. It has been found that LPE growth at Tapproximately equals 5300C produces good quality Ga1-xAlxAsySb1-y layers with Al content in the solid up to x equals0.24 and latice mismatch (delta) a/a not exceeding 5*10-4. As for the growth of higher aluminum content alloys at higher temperatures Tequals590 - 6000C, good results have been obtained unless the Al content in the melt does not exceed xAl1equals0.02 giving perfectly matched Ga1- xAlxAsySb1-y epilayers with Al content in the solid by up to x equals0.3. By introducing an interlayer, either of the lattice matched Ga0.91In0.09As0.08Sb0.92 or Ga0.70Al0.30As0.03Sb0.97, LPE growth from the melt with Al content up to xAl1equals0.06 becomes possible and enables fabrication of Ga1-xAlxAsySb1-y layers with Al content in the solid as high as xequals0.62. Ga1-xAlxAsySb1-y layers obtained from the melt with xAl1equals0.04 were characterized by lattice mismatch (Delta) a/aequals(8-9)-10-4, an increase of (Delta) a/a to 2.2*10-3 was observed for epilayers obtained from the melt with xAl1equals0.06.

The effects of various chemical treatments on (100) GaSb surface with the aim to develop procedures of polishing of GaSb substrates, surface preparation prior to LPE growth, metal and dielectric deposition, fabrication of patterns have been examined. We show that chemomechanical polishing in Br2 - ethylene glycol followed by anodic oxidation and oxide removal enables to fabricate damage free GaSb surface with the roughness of about 1.5 nm. Surface treatment in 30 HCL-1HNO3 followed by 5%HCL etch gives the best results for surface cleaning prior to metal deposition. The optimum pre-epitaxial treatment includes the use of 1M Na2S solution and H2 anneal. For features patterning 60HCL-1H2O2-1H2O enables etching at rate of approximately 4 micrometers /min, however, to achieve highly anisotropic etching of small size features the use of Ccl4/H2 plasma is the most suitable.

Pb1-x-yGexSnyTe:In thin films were made using hot wall modified method. The composition of grown films approximately corresponds to the initial composition of the polycrystalline charge when using this method. Maximum observed concentration deviation (in comparison to charge) of different components in resulting films was: (Delta) nPbGeSn

The successful fabrication of long wavelength Hg1-yCdyTe/Hg1-xCdxTe heterostructures (Y$GTRx) on semi- insulating (111)CdZnTe substrates is presented. The heterostructures consist of a thin 2-5 micrometers layer on n-type 10- 15 micrometers thick HgCdTe epilayer. A novel tipping boat for liquid phase epitaxial growth of mercury cadmium telluride from Te-rich solutions has been proposed. The characterization of double- layer heterostructures was carried out using different methods: microscopic examinations, infrared microscopic transmission, and scanning electron microscopic measurements. Electrical properties were measured in temperature range of 77-300 K using the Van der Pauw arrangement. By optimizing the growth parameters and the construction of graphite boat it was possible to obtain high quality, relatively abrupt Hg1-xCdxTe heterostructures.

A concise review of the history and of the basic physics of the Wigner crystal (electron solid) in two dimensional electron systems in semiconductor heterostructures is given. The results of our experimental study on the formation and of the properties of the magnetic field-induced insulating phase, supposed to be a Wigner crystal, in a two dimensional gas in In0.53Ga0.47As/InP heterostructures are surveyed. These structures are characterized by a much greater disorder potential than AlGaAs/GaAs heterostructures due to the inherent alloy disorder in the InGaAs layer supporting the two dimensional electron gas. In high magnetic fields, below a Landau level filling factor of 0.4-0.5 divergent resistivity, non-linear current-voltage characteristics with a threshold, and a transition from non- activated to activated transport were observed. A model is proposed for the Wigner crystal-like ordering of the two dimensional electron gas in this system with large disorder.

X-ray diffraction and synchrotron x-ray topography methods were used to analyze strain in GaAs layers grown on GaAs and Si substrates by epitaxial lateral overgrowth (ELO) from a liquid phase. We show the laterally overgrown parts of ELO stripes adhere to the SiO2 mask which results in their downwards bending. The procedure was found which allows to control adhesion of the layers to the mask by adjusting the vertical growth rate of the layers. For the case of GaAs ELO layers grown on Si substrates the ELO stripes bend outwards from the mask due to the tensile strain in the GaAs buffer layer. Recent data published on strain in other than GaAs ELO structures are reviewed and compared with our results.

Experiments on preparation of C60ONCFn cycloadduct (Fn=ferrocene) and C60(Cocp2)3 charge transfer complexes are described and their properties analyzed. The ferrocene derivative is bound to C60 at the 6-6 bond by a heterocyclic oxygen-nitrogen-carbon ring. The experimental results are compared with the results of modeling using semiempirical quantum chemistry PM3 model. Scanning tunneling microscopy and spectroscopy has been used to observe variation of electronic structure along capped carbon nanotubes deposited on freshly cleaved HOPG(0001) surface. The electronic structure has been derived from measured dependence of tunneling conductance dI/dV on the applied voltage. The evolution of dI/dV(V) along the nanotube are discussed in terms of existing theories of nanotubes and quantum chemistry calculations.

We have studied the physical processes, which underlie the operation of a vertical quantum-dot nanodevice as a single- electron transistor. The Poisson-Schroedinger problem has been solved for the entire nanostructure. We have calculated the charge density on the quantum dot/gate electrode interface and the distribution of the ionized donors in n-GaAs layers close to the quantum-dot region. We have found that the characteristic rapid variation of the distribution of the ionized donors is responsible for the essential change of the electron confinement potential, which leads to a strong modification of the single- electron tunneling.

A simple theory of the quantum interference due to spin coherence and Larmor procession of the electron spin is proposed. A spin ballistic regime in a loop structure is assumed, where the phase relaxation length for the spin part of the wave function (Lphi(e)) is much greater than the relaxation length for the orbital part (Lphi(s)). In the presence of additional magnetic field, the spin part of the electron's wave function acquires a phase shift due to additional spin precession about that field. If also the structure length L is chosen such that (formula available in paper), it is possible to wash out the quantum interference related to the phase coherence of the orbital part of the wave function, retaining at the same time that related to the phase coherence of the spin part, to reveal the corresponding conductance oscillations. It is also emphasized that strong modulation of the conductance of the structure could be achieved in this way.

MBE-grown In (formula available in paper)As/GaAs double quantum dot structure has been investigated by photo reflectance (PR) spectroscopy. Features related to all the relevant portions of the sample including the quantum dots and wetting layers have been observed at 10 K. The PR results have been supported by the standard high-excitation photo luminescence (PL) measurements revealing excited state transition due to the effect of higher level filling. The experimental transition energies have been compared to the results of the effective mass approximation calculations for double quantum wells and lens-shaped double quantum dots. The evidence of the dot-dot and wetting layer well-well interaction has been found.

Results of the resistance studies on p-type germanium micro crystals grown in form of whiskers are presented. The crystals were brought to the vicinity of the metal-insulator transition (MIT) at liquid helium temperatures by doping with gallium and with some deep level impurities. A special technique has been developed to obtain these crystals anisotropically strained at cryogenic temperatures, so that both uniaxial tension and compression are achieved. The region adjacent to the MIT from both insulating and metallic side has been studied and some practical recommendations have been elaborated.

Proc. SPIE 4413, Effect of the alpha-particle irradiation on the photoluminescence and Raman spectroscopy from GaAs/Al0.3Ga0.7As quantum wells and coupling coefficients for the light and heavy holes, 0000 (17 April 2001); doi: 10.1117/12.425419

The epitaxial grown GaAs quantum wells (Qws) (with the width L1=2.5nm and L2=15nm) were subjected to alpha particle irradiation at doses (7.8*1012-3.4*1013)cm-2. The response of the Qws was studied by means of the low temperature photo luminescence (PL) and inelastic light spectroscopy. The damage accumulation leads to a shift of the quasi particle energy level towards higher energy and to a decrease of the LO1 and LO2 modes and to an increase of the TO2 frequency mode of the Al0.3Ga0.7As slabs.

Unexpected excess current was obtained in GaAs/InAs quantum dot structures at low temperatures and low current levels. This excess current exhibited instabilities with changing the bias, and over the time. It has been concluded that the excess current is a minority injection current connected with the high recombination rate through quantum dots. The instabilities are connected with unstable charge occupation of quantum dots.

Photoluminescence time resolved spectra (PL-TRS) and decay curves of photoluminescence (PL-DC) in the wavelength range 400-850 nm in micro and nanosecond time range at different temperatures (10K-room) on anodically etched boron doped porous silicon are presented. PL-TRS exhibit multiband structure and can be decomposed as a sum of few Gaussians. Positions of gaussian emission bands depend on temperature and change similar to thermal profile of the energy gap of the bulk silicon. PL-DC have multi exponential shape. Relaxation times depend on wavelength of the observation and temperature. At low temperature decay times dramatically increase (from few microsecond(s) at 300K to some hundred microsecond(s) ) and short component in nanosecond range has been observed. To explain our results we assumed model in which the multi barrier structure is formed by Si crystal (quantum well) surrounded by Si crystallites with diameters in the nanometer range (barrier region). The visible photoluminescence originates from radiative recombination between discrete energy levels in quantum well regions. Short component of decay at lowest temperatures is connected to non-radiative Auger relaxation inside porous silicon structures.

Amorphous nano-powders of Pb(Zr0.5Ti0.5)O3 (PZT) solid solution were obtained by sol-gel method. As obtained nano-powders of mean dimension rapproximately equals 30 nm underwent consolidation by conventional ceramic sintering, hot high pressing, or rapid thermal annealing. As a result PZT ferroelectric ceramics exhibit lack of voids, density close to the theoretical X-ray density, homogeneity from both chemical and physical point of view and stoichiometric chemical composition. The nanocrystalline structure of the ceramics grains has been revealed by X-ray diffraction method. Dimension of the crystallites (Dequals20-75 nm) were found to depend on temperature (Ts) and the rate of sintering (vT$. Of the sol-gel-derived powders. Dielectric and piezoelectric properties of the obtained nanocrystalline PZT ceramic samples varied with both sol-gel processing conditions and sintering conditions.

We report here on the development of host-guest and guest-guest interaction in course of preparation procedures semiconductor clusters (CdS, PbI2), in zeolite (FAU,LTL) matrix. Optical properties of practically unexplored PbI2/zeolite LTL system have been investigated. Both in absorption (reconstructed from diffuse reflection via Kubelka-Munk function) and luminescence spectra the features were observed at energies much exceeding the excitation resonance energy Eex in bulk PbI2. This is considered as an indication of size quantization through the unambiguous attribution of the respective transitions requires further studies, including theoretical ones. For the samples with relatively high PbI2 content the narrow emission peak only slightly blue-shifted from Eex was observed and attributed to long clusters formed inside the main channels of zeolite LTL lattice and possible retaining the layer structure of bulk PbI2. The gradual disappearance of this peak during the storage of samples in the air is explained by assuming that originally formed long clusters undergo fragmentation into smaller species.

Nano structured Lu2O3, both plane and doped with Tb, was prepared utilizing a combustion technique. The best crystallity of the products can be obtained initiating the reaction within 560-700 $DEGC range of temperature. Tb easily enters the nano scaled host lattice both as Tb3+ and Tb4+. The former gives rise to a typical green emission of the ion, while the later introduces a broad-band visible absorption, due to charge transfer transitions. The green emission of Tb3+ from a raw material may be radically increased by after- preparation heat-treatment. Undoped material gives rise to a blue emission, which disappears when Tb content with respect to Lu reaches 0.0001% or higher level.

We present results of experimental investigations of Ni clusters deposited on ab surface of Bi2Sr2CaCu2O8+y (BSCCO) single crystals or highly oriented pyrolytic graphite (HOPG) substrates. The micro clusters were produced by the plasma gas condensation or evaporator with integral flux monitor. The scanning tunneling spectroscopy was performed at 24K and at room temperature. The spectra reveal differences between the curves measured above the Ni clusters and substrate, respectively. The relationship between surface atomic scale and local density of states in the materials is also discussed.

We report on a comparative investigation of as grown and alpha particle irradiated Ga-As-nipi doping super-lattices. We have used inelastic light scattering and low temperature photoluminescence spectroscopy to study the change in structural as well as electronic properties. Depending on the dose of alpha particles, we have found that the degree of structural damage varies. The PL spectroscopy shows that the main, e-Zn(h), band shifts toward higher energy (with a decrease in intensity). After annealing, partial recovery is found.

The polycrystalline thin diamond films grown by HF CVD technique have been studied by FTIR, ESR, X-ray, Raman and photoluminescence spectroscopy. Pl spectra were recorded in temperatures range of 10-300K. The thermal behavior of the broad band luminescence indicates a D-A pair recombination process. The defects taking part in luminescence can be associated with hydrogen related centers. The presence of hydrogen in the diamond layers has been confirmed by FTIR and ESR measurements.

PbSe thin layers were grown by pulsed laser deposition. The layers were obtained on Si substrates at temperature 45K to 650K. The structure of the layers and its lattice parameters were estimated from the X-ray diffraction measurements. The strong intensity of (200)-PbSe peak indicates a self-texture preference in the c-axis direction.

High resolution photo induced transient spectroscopy has been utilized to study defect centers in semi-insulating molecular beam epitaxy GaAs grown at temperatures 300 and 400 $DEGC. A number of traps with activation energies ranging from 0.004 to 0.64 eV have been detected. The traps are tentatively identified with native defects in GaAs lattice. The effect of the growth temperature on the defect structure of the layers is shown.

Deep states in semi-insulating Si are investigated by analyzing of two-dimensional Photo-Induced Transient Spectroscopy (PITS) spectra. The results exemplify new potentialities of the advanced computer programming technique.

The modulated photo current measurements (MPC) are performed in frequency domain. The excess charge carriers are generated by light source, the intensity of which is sinusoidally modulated. The phase shift between excitation and photo current is dependent on the frequency and temperature. The parameters of defect levels are estimated from this shift.

The technique of low frequency noise vs temperature is a powerful tool for study of deep level impurities in semiconductors materials. The physical parameters of the deep level defects are possible to identify from noise data. Measurement system to measure low noise spectra in frequency range from 0.01 kHz at temperature from 77K to 350K has been described.

Electrical properties of the electroluminescent thin film cells based on zinc sulfide were investigated. Current-voltage characteristics for whole electroluminescent cell and part of the cell were measured at room temperature. Current-voltage characteristics due to part of the cell were performed by point contact tunneling method. In both the kind of current-voltage characteristics memory effect has been observed. Different mechanisms of the charge transport through the cells and thin ZnS:Mn,Cu films were taken into account. We have found that it is more than one mechanism of electrical conductivity in the thin films.

In this work the results of m-terphenyl polycrystalline thin films investigations are presented. The main purpose of the investigations was to determine the mechanism of DC conductivity in the disordered m-terphenyl polycrystalline structures. The measurements were carried out for the thin films of m-terphenyl of the thickness varied from 2 to 13 micrometers with the presence of an external electrical field, which strength varied from 0 to 106 V/cm. Applied temperature range was 15-325K. The investigated m-terphenyl thin films were supplied with either the gold and Aluminum or the gold and carbon electrodes. The determined values of activation energy were found to be in the range of kT to 0.2 eV. The study let us determine the influence of an external electric field on the height of the potential barriers between the trapped charge carriers. The results obtained as well as their analysis drive to a conclusion that an injection of an electric charge from the electrodes into the investigated material's bulk takes place through the thermoemission and field emission processes.

Results of an in-situ STM study of homoepitaxial copper electro deposition on Cu(111) in 0.01 M H2SO4 solution are presented which show a pronounced change in the growth and morphology of the deposit with increasing potential: while at - 0.40 V vs. SCE Cu multilayer growth is observed, Cu grows via a step-flow mechanism at -0.55 V. This behavior can be explained by the presence of an ordered sulfate adlayer at potentials >=-o.42 V, which causes a pronounced decrease in the Cu surface mobility.

New experiments are reported which explore the influence of the hydrostatic pressure during post-implantation annealing on the photoluminescence (PL) from silicon oxynitride layers (SiOxNy, x=0.25, y=1) implanted with Ge+ ions. It is shown that the use of a hydrostatic pressure during heat treatment results in an enhancement of the PL intensity by an order of magnitude compared with that arising from anneals carried out at atmospheric pressure. The observed increase in the PL intensity is explained in terms of the enhanced formation of radiative recombination canters within meta-stable regions of the implanted silicon oxynitride. The nature of these centers is believed to be associated with the equalsVSi-SiequalsV) center and defect complexes incorporating Ge atoms (e.g. equalsVSi-GeequalsV) or equalsVGe-GeequalsV) centers).

Principles and applications of the cantilever technique to measure strain and stress in thin films are presented. Different optical interferometers were created and applied to control stress-thickness dependence during technological processes or to measure two-dimensional strain distribution in thin film. An original scheme combining advantages of the classical interferometer and electronic speckle pattern interferometer is presented.

Magnetophonon Resonance in parallel transport of three types of Multiple Quantum Wells was studied. They consisted of ten QW of GaAs and ten AlGaAs barriers, and were obtained by the Metal Organic Vapor Deposition an semi-insulating GaAs. The MPR research were performed in pulsed magnetic fields up to 30 T. The transverse magneto resistance was measured between 77K and 340K and the MPR oscillations extracted by subtracting a voltage linear in magnetic field. The oscillating part of magneto resistance (Delta) (rho) xx was recorded. A fine structure of MPR peaks was observed. This effect could be attributed to two phenomena: contribution of barrier phonons and influence of thermostresses.

Photoreflectance (PR) spectroscopy has been applied to the investigation of Si (delta) -doped AlxGa1-xAs layers grown by metal-organic vapor phase epitaxy on GaAs substrates. Measurements have been carried out on samples with aluminum content of 0,0.35 and 1. The observation of Franz-Keldysh oscillations (FKO) in a number of more than 10 (in the best case) and application of the fast Fourier transformation has allowed us to determine the internal electric field with high accuracy. Thus, the potential barrier between surface and (delta) -doped region has been estimated. Finally, the contribution of heavy and light hole related transitions to the FKO has been resolved.

The electrical and photo electrical behavior of Au/n-CdTe junctions prepared no CdTe mono crystalline substrates were studied. Both properties depended strongly on the parameters of the compensated high-resistive layer at the CdTe surface formed by annealing in air during preparation.

The effect of high temperature-high pressure (HT-HP) treatment of semiconducting layers on their structural properties was investigated by X-ray methods. The changes of the strain state of the samples induced by the HT-HP treatment depend on the initial strain state and growth method of thin layers. Only for the layers obtained by MBE methods the change of strain state of layers was found. Decrease of the dislocation density was detected for relaxed InAs/GaAs layers after the treatment at 673K - 1.1 Gpa for 1 h. For strained AlGaAs/GaAs samples the pressure - induces stress is responsible for creation of dislocation.

Substrate temperature is one of the important deposition parameters, which dictates many physical properties of thin films to a large extent. This paper deals with the effect of substrate temperature on the optical properties of Chromium films in the thickness range 5-80 nm. Soon after the growth the films were taken out of vacuum chamber and used in the transmittance measurements using DK2 Ratio Recording Spectrometer in the visible region of incident radiation, for both the films grown at substrate temperatures 27DEGC and 180DEGC. From the transmittance data of the films, we have evaluated the optical constants, refractive index, band gap and extinction coefficient for both the films. Using Lambert's Law the absorption coefficient is also calculated for both the films.

Spectra and kinetics of SnOx-ZnS-CuxS-ZnS:Mn-Al electroluminescent cells were investigated for different dc voltage applied. Both zinc sulphide films and aluminum films were produced by thermal evaporation in a vacuum of about 10-5Tr. The thin tin oxide films were prepared by spray technique, based on the pyrolysis of an aerosol on the surface of heated glass substrate. The CuxS layer was made by wet chemical process. The cells exhibit yellow-orange emission with a maximum at about 585 nm. Kinetic measurements indicate that the decay curve of the electroluminescence can be usually expanded in two exponentials. These exponentials are due to two kinds of manganese centers: Mn2+ ions with longer lifetime t1 and Mn2+-Mn2+ pairs with shorter lifetime t2. The values of the lifetimes depend on manganese concentration, temperature and types of crystal sites. The lifetimes are rather shorter for thin films and longer for crystals and powder phosphors. When a short voltage pulse is supplied to the cells, the maximum of the electroluminescence appears after the end of the exciting pulse. The phenomenon can be explained assuming energy transfer from one monomolecular center to another. The electroluminescence spectra were measured for several applied voltages from 18 to 100V. It was found that the spectrum becomes broader for higher voltages, mainly on the short-wavelength side of the spectrum. Additionally, the voltage dependence of the manganese lifetimes was investigated. The values of the lifetimes are longer for higher voltages.

The thin transparent and conductive Sn doped In2O3 layers have been deposited onto both surfaces of the glass plate of dimensions 0.2x16x16 mm using the constant-current ion sputtering method. In order to study the electron emission the voltage has been applied between both the ITO layers. One of the layers was 1 micrometers thick (the field electrode) and another one (10nm and much thinner) was deposited onto the opposite surface of the glass. This thin layer was treated as the electron emitter. The polarizing voltage Upol has been applied to the field electrode. The study has been carried out in vacuum (10MIN7hPa). The multichannel analyzer of amplitude of voltage pulses created by the electron multiplier has been used in order to record the electron emission yield. Aside of the field effects the studies concerning the result of UV illumination on the photo emission monitored by field has been examined. Determined were the amplitude spectrum of the voltage pulses for various polarizing voltage. The same method was used to find the dependence of the pulse frequency n on the applied voltage Upol. The exponential dependence n = f(Upol) has been found. The field induced emission mechanism can be explained on the basis of the well known phenomena occurring in semiconductors under influence of strong electric field (the hot electron effect, the impact ionization, the Gunn effect, the tunnel effect, etc.). It was also found that additional effect at simultaneous emission of two electrons as a result of absorption of a single photon have to be taken into account. The existence of this effect has been proved by decomposition of the amplitude spectrum into Gaussians. Measurements of electron energy in the field induced emission showed that about 80% of electrons have energy up to 10 eV. Photo induced optical second harmonic (SHG) has been also observed in these films.

The world at the end of the 20th Century has become blue. Indeed, this past decade has witnessed a blue rush towards the development of violet-blue-green light emitting diodes (LEDs) and laser diodes (LDs) based on wide band gap III-nitride semiconductors. And the hard work has culminated with, first, the demonstration of commercial high brightness blue and green LEDs and of commercial violet LDs, at the very end of this decade. Thanks to their extraordinary properties, these semiconductor materials have generated a plethora of activity in semiconductor science and technology. Novel approaches are explored daily to improve the current optoelectronics state-of- the-art. Such improvements will extend the usage and the efficiency of new light sources (e.g. white LEDs), support the rising information technology age (e.g. high density optical data storage), and enhance the environmental awareness capabilities of humans (ultraviolet and visible photon detectors and sensors). Such opportunities and many others will be reviewed in this presentation.

The development of devices for mid-, long-, and very long- wavelength IR detection has benefitted greatly from advances in band-gap engineering. Recently, there has been great progress in the development of n-type GaAs/AlGaAs quantum well infrared photoconductor (QWIP) detector arrays in all three technologically important wavelength windows. P-type GaAs.AlGaAs QWIPS represent a viable alternative to n-type GaAs/AlGaAs QWIPs, offering the advantage of normal incidence absorption without the need for grating couplers. The maturity of the MBE of GaAs/AlGaAs layered materials offers the possibility of mass producing low cost, high performance, large size, high uniformity, multicolor, high frequency bandwidth, two-dimensional imaging QWIP arrays. This paper describes progress in optimizing the performance of p- type GaAs/AlGaAs QWIPs through modeling, growth, and characterization. Using the 8x8 envelope-function approximation (EFA), a number of structures were designed and their optical absorption calculated for comparison with experiment. Samples were grown by MBE based on the theoretical designs and their photoresponse measured. P-type QWIPs were optimized with respect to the well and barrier widths, alloy concentration, and dopant concentration; resonant cavity devices were also fabricated and temperature dependent photoresponse was measured. The quantum efficiencies and the background-limited (BLIP) detectivities under BLIP conditions of our own p-QWIPs are comparable to those of n-QWIPs; however, the responsivities are smaller. For our mid-IR p-QWIPs, the 2D doping densities of 1- 2x1012 cm-2 maximized the BLIP temperature and dark current limited detectivity by operating at around 100K. At 80K, the detectivity of the optimum doped sample was (formula available in paper)at 10V bias. Barrier widths greater than 200 A were sufficient to impede the tunneling dark current; resonant cavities enhanced absorption five-fold.

The paper presents progress in infrared (IR) detector technologies during two hundred history of their development. Classification of two types of infrared detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. The overview of infrared systems and detectors is presented. Recent progress in different IR technologies is described from a historical point of view. Discussion is concentrated mainly on current and the most rapidly developing detectors: HgCdTe heterostructure photodiodes, quantum well AlGaAs/GaAs photoresistors, and thermal detectors. The outlook for near-future trends in IR technologies is also presented.